Severe wind gusts associated with mid-latitude convective storms contribute to an increasing amount of natural hazard related losses in Europe. Modifications of the atmosphere associated with anthropogenic climate change are projected to increase the frequency of favorable conditions for convective storms, and it is absolutely critical to understand the implications of these changes to prepare for a resilient future. To this end, the fate of convective gusts in Europe in a future warmer climate is addressed through the output of two high resolution regional climate models (RCMs). One RCM includes convection permitting (CP) physics, and the other assumes hydrostatic conditions in which deep convection is parameterized. It is found that the magnitude and characteristics of extreme straight line gusts from mesoscale convective systems are well resolved in the CP-RCM but not in the hydrostatic RCM. The RCMs are forced with a high carbon emission scenario for the end of the 21st century, and the CP-RCM shows an increase in the frequency and magnitude of extreme convective gusts over mainland Europe. These changes are likely related to an increase in conditions where strong wind shear (≥15 m/s) simultaneously occurs with unstable environments (lifted index ≤-2). However, the inherent low frequency of extreme convective storms requires continued investigation to draw more robust conclusions. In addition, the environmental conditions in which the severe gusts take place indicate the importance of addressing gusts separately from the more commonly studied effects of climate change on extreme convective precipitation. This thesis provides an important bridge to understand the fate of extreme gusts from convective storms in a future warmer climate and the high potential of CP-RCMs in such studies.

As I am writing this, parts of Central Europe are plagued by a series of intense rainfall events that, in less than two days, turn rivers into powerful streams, cause flooding, damage infrastructure and property, and harm people. The number of such extreme events, which are associated with high economic losses and casualties, has been increasing for decades. How is this happening? And, what is the relation between extreme convective precipitation events and increasing temperatures, such as which we are currently experiencing due to climate change? To tackle these questions, consider the following simplified version of a convective rain event. We imagine a column of air, a part of the atmosphere with a cloud inside of it. Near the surface, air streams into the column where it starts rising vertically. While gaining height, the air cools, until at a certain level the contained water vapor will condensate in the formof small cloud droplets. From this level, the cloud base, the air mass continues ascending while the amount of condensed water keeps increasing, so that the cloud droplets grow in size. Finally, when they grow sufficiently large, precipitation will set in, and, in the most extreme case, all the cloud water will reach the ground as rain. Following this conceptual model, one way to increase the amount of precipitation is to increase the moisture content of the air that enters the cloud.@en